Lithium (Li) is used in advanced clean energy technologies including fuel cells, electric vehicles, and other applications as Li-ion batteries. Because of its importance in energy storage devices, it is listed as a near-critical material (2nd highest ranking) element in the US DOE 2011 Critical Materials Strategy. Lithium is often isolated from hypersaline fluids or brines. Natural geothermal brines are hydrothermal fluids heated by natural heat under earth's surface. Natural geothermal brines are an environmentally preferred and renewable energy source.
In the early 1990s, the United States was the largest producer and consumer of lithium minerals and compounds worldwide. Between 1995 and 2004, production shifted to South America where production costs were far lower. Now, the U.S. largely relies on foreign sources of Li due to limited domestic supply.
The current leading technology to extract Li from brines requires a series of football field-sized evaporation ponds, lengthy (approximately 18-24 months) leaching processes, consuming time and energy, and emitting CO2. During the evaporation stage, large quantities of diesel fuel are consumed producing additional carbon dioxide. After concentration, the Li-rich brines are generally required to be transported a long distance to a processing plant that produces Li compounds; such as lithium carbonate (Li2CO3), lithium chloride, and lithium hydroxide; by multiple carbonation steps. This carbonation process requires various solid additives including: soda ash (Na2CO3), lime (CaO), hydrochloric acid (HCl), organic solvent, sulfuric acid (H2SO4), and alcohol. A total of 2.7 ton of the combined additives may be required to produce a ton of Li2CO3 in these processes. Excluding land transit of the concentrated brine solutions, the currently leading carbonation operation may consume more than 10 GJ/ton Li2CO3 produced (or $208/ton of Li2CO3 production@$0.07/kWh).
There is, therefore, a need for a method for domestically generating solid lithium carbonate that requires less time, energy, waste, and is produced at a lower cost than existing technology.